Sometimes the blood oxygen level doesn't work. I thought if a bigger area in the sensor, or a smaller on, it might be more focused. The watch runs great, holds the charge, has the current updates. I am going to wait until the sensor has something I can use such as glucose readings, but then again.... it might only read a non evasive attached probe. Not really non evasive, they do have a tiny probe that goes into the skin. Oh well, I can wait, and if I should kick off, well it won't matter. I do know when I do change, it is going to be red. arghhhh